[Amps] ETO 91b help please.

[robert.thain@ratp.fr]

ETO 91b help please.

I recently bought my first amp, a 91b second hand.

It was demonstrated to me working fine on a real antenna, (not a dummy
load).
I went to use it for the first time for the ARRL 10M.
It has the 10m modification for outside the US, the tapping on the
transformer is correct for 220V.
The relay was switched manually and not by the radio.
The SWR on the antenna is about 1.2:1and has been used with amps before.

I followed the tune up procedure in the booklet enclosed with the amp, but
it just 'faults out" every time.
In the booklet it suggests starting with Tune = 40 and Load =80.
Once I have followed the procedure I end up with Tune = 10 and Load = 0.
As I increase the power I get to about  800w out, then it trips.

I do not think it is normal for the Load to be so low.
What am I doing wrong?
I am an 'antenna' ham and not a 'radio technical ham', this is a (big and
bloody heavy) black box to me, so please keep it simple if its possible.

Thanks

Robert 
G0HGW